Hi, I am facing a strange issue. i need to use in an Azure function some native dll (x64 dll). Locally function works but when deploy function to Azure I obtain a BadImageFormat exception when native dll are called. I set 64 bit on Azure portal, compiling with x64 and publishing with Configuration Release x64 and target runtime win-x64. i use Net Core 3.1 and Azure Function 3.0.9 Am i missing something?

@Erasmo Solazzo By default apps are actually set to run on 32-bit . But, you have also confirmed to modify the bitness from portal. ( could you share a screenshot) It may be worth looking into the bin/ of the build and seeing if you see the right runtimes/ folder being generated with native libraries. Could you also share the entire call stack of the exception? Also, Please follow these steps: Go to https://resources.azure.com/ Find your function app, and go under config/web under it in the tree check the value of use32BitWorkerProcess, whether it is false. Please let me know if this helps.

Azure Function with native dll x64

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JayaC-MSFT 5,531 Reputation points

2020-09-01T11:27:43.543+00:00
@Erasmo Solazzo By default apps are actually set to run on 32-bit . But, you have also confirmed to modify the bitness from portal. ( could you share a screenshot)
It may be worth looking into the bin/ of the build and seeing if you see the right runtimes/ folder being generated with native libraries.
Could you also share the entire call stack of the exception?
Also, Please follow these steps:

Go to https://resources.azure.com/

Find your function app, and go under config/web under it in the tree

check the value of use32BitWorkerProcess, whether it is false.

Please let me know if this helps.
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1 person found this answer helpful.
Erasmo Solazzo 56 Reputation points

2020-09-02T17:43:48.29+00:00

Value of use32BitWorkerProcess is false.
I attached azure portal and visual studio configuration, it is all x64.

I speculated that problem can be visual c++ redistributable lack.
I added needed dll into bin folderwith function dll, but I receive always the same exception: An attempt was made to load a program with an incorrect format.

Have I to put redistributable dll into some other folders?

JayaC-MSFT 5,531 Reputation points

2020-09-03T06:53:08.08+00:00

You don't have to explicitly load/install it. Azure App Service is a PaaS offering running in a sandbox and the required libraries are already installed.

You may refer to this to check which package is installed for your app service. [ Note : as this document is old you may not see the latest VS example but it would guide you to check the version details of the library]

Also, could you please share the folder structure details where you have put the dll.

Suggestion : You may consider running the application in an Azure VM where you can manage the OS and the installed libraries yourself and see if you are still encountering this problem ( if this option is feasible at all)

JayaC-MSFT 5,531 Reputation points

2020-09-03T07:00:35.363+00:00

For the error message , it is generally because of the mismatch in bitness. Please check :
https://www.techinpost.com/an-attempt-was-made-to-load-a-program-with-an-incorrect-format/ and
https://stackoverflow.com/questions/2023766/an-attempt-was-made-to-load-a-program-with-an-incorrect-format-even-when-the-p

Erasmo Solazzo 56 Reputation points

2020-09-03T08:09:35.987+00:00

I check with reg query and Redistributable 2013 and 2015-2019 (that my library need) are absent.

I test on a VM without these libraries and I obtain the same exception. Putting redistributable dll in exe folder it works.

I think that azure function runtime folder is not bin folder.
Redistributable dll are in folder D:\home\site\wwwroot\bin where function dll is located.

Can I access to folder where process is running and putting there dll redistributable or update Path enviroment variable to specify folder bin?

JayaC-MSFT 5,531 Reputation points

2020-09-03T09:12:28.32+00:00

Azure App Service/Azure Function runs in a secure environment called a sandbox which imposes certain limitation. Limitations like playing around some com components , writing to registry , User32/GDI32 restrictions. The sandbox is described here. ( already mentioned in the previous comment)

I am afraid you won't be able to access the console and install any 3rd party libraries which run via a script, ex: EXE or MSI.

So if you have anything related to any of these Sandbox restriction then going for Azure VM will make more sense. I believe you have already tested with Azure VM and it works fine for you.

If you think this answer helped , please "Accept the answer" and "Up-vote" so that it can help others in the community.

Erasmo Solazzo 56 Reputation points

2020-09-03T15:12:47.297+00:00

Ok.

I was working with function for consuption plan feature so a VM is not a feasible solution.
I will evaluate other scalable solution like AKS with KEDA or alternatively other cloud vendor.

Thank you
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